Sleep apnea is a disorder in which the patient actually stops breathing while asleep. After an apnea episode, the person awakens, gasping for air, but is not aware that sleep has been disrupted. Sufferers of apnea often experience excessive daytime sleepiness, and in severe cases, may be at increased risk for high blood pressure, diabetes, stroke and heart attack

People with insomnia have chronic problems with falling asleep or staying asleep, usually due to underlying psychological or physical problems.

Narcolepsy is probably the most difficult sleep disorder to properly diagnose. It is a chronic, neurological disorder involving a person’s central nervous system. Symptoms can include a sudden loss of muscle control, intense emotional experiences, sleep paralysis, vivid dreams or hallucinations while falling asleep, and unexpected 'sleep attacks'.

People with this syndrome often experience restlessness or uncomfortable sensations in their legs or arms, particularly in the evening or when resting, which may cause difficulty falling or staying asleep.